1. Field of the Invention
The present invention relates to a technique for generating a pulse.
2. Description of the Related Art
Pulse width modulation is used to drive and control an electronic circuit controlled by a switching pulse signal, examples of which include a switching regulator, a motor, etc. In pulse width modulation, the electrical state of the electronic circuit is fed back, and the pulse width of the pulse signal is adjusted based upon the feedback signal. In a case in which a switching regulator (DC/DC converter or DC/AC converter) is driven, the pulse width of the pulse signal is adjusted such that the feedback voltage that corresponds to the output voltage matches a predetermined reference voltage. In a case in which a motor is driven, the pulse width is adjusted such that the electric current that flows through a coil of the motor matches a predetermined electric current.
In an arrangement in which the pulse width modulation is provided by means of a digital circuit, a clock signal is generated at a frequency that is sufficiently higher than that of the pulse signal, and the clock signal thus generated is counted by a counter, in count increments that correspond to the pulse width, thereby generating pulses having a desired pulse width.
[Related Art Documents]
[Patent Documents]
[Patent Document 1]
US patent publication 2007/126410A1 Specification
The aforementioned method requires a clock signal generated at a frequency that corresponds to the resolution of the pulse width of the pulse signal. Accordingly, such a method providing high pulse width resolution requires an oscillator which oscillates at a high frequency, leading to increased power consumption by the circuit.